A novel chlorin derivative of Meso-tris(pentafluorophenyl)-4-pyridylporphyrin: synthesis, photophysics and photochemical properties

Abstract

A terapia fotodinâmica (TFD) está baseada na administração e no acúmulo de fotossensibilizador, por exemplo, de tipo porfirina ou clorina, em tecidos doentes. As clorinas apresentam propriedades fotofísicas semelhantes àquelas das porfirinas, mas com intensificação e deslocamento das bandas Q, o que faz com que sejam bons candidatos para TFD. Neste trabalho relata-se a síntese da 5,10,15-tris(pentafluorofenil)-20-(4-piridil)porfirina, (2), e das clorinas isômeras 4, (5,10,20-tris(pentafluorofenil)-15-(4-piridil)-tetra-hidro-1H-N-metil-pirrolo[3,4-b]porfirina e 5, (5,10,15-tris(pentafluorofenil)-20-(4-piridil)-tetra-hidro-1H-N-metil-pirrolo[3,4-b]porfirina, obtidas a partir de 2, por reação de cicloadição 1,3-dipolar com um ileto azometínico, e respectivas caracterizações estruturais por UV-Vis, RMN e EM-FAB. Foram avaliadas as propriedades fotofísicas, fotoquímicas e fotodegradativas para a nova clorina 4, obtida com melhor rendimento que o seu isômero 5. O rendimento quântico de fotodegradação (φ Fd , mol Einstein -1 ) foi de 0,047±0,014. Foram ainda realizados testes com ácido úrico para demonstrar a capacidade do fotossensibilizador na produção de 1 O 2 . Os resultados mostraram que a nova clorina 4 pode ser considerada como um bom fotossensibilizador para TFD.Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorin, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorin-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorin derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H-N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H-N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, 1 H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorin 4 have been evaluated. Its quantum yield of photobleaching (φ Pb , mol Einstein -1 ) was 0.047±0.014. In order to demonstrate the production of 1 O 2 when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorin 4 can be considered a promising photosensitizer in PDT.

Charge effect on the photoinactivation of Gram-negative and Gram-positive bacteria by cationic meso-substituted porphyrins

“…Porphyrins were purified by crystallization from chloroform-methanol-petroleum ether and their purities were confirmed by thin layer chromatography and by 1 H NMR spectroscopy. The spectroscopic data was in accordance with the literature [38-40]. Stock solutions (500 μM) of each porphyrin in dimethyl sulfoxide were prepared by dissolving the adequate amount of the desired porphyrin in a known volume.…”

Photostability of different chlorine photosensitizers

“…Chlorines exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorine-containing systems even better candidates for PDT [5][6][7][8][9][10].…”

Photobleaching of Sn(IV) chlorine e6 dichloride trisodium salt in different environments

“…Porphyrin's derivatives, which are hydrophobic in nature, showed a strong decrease in the absorption at all bands in buffer (Belitchenko et al, 1998;Maestrin et al, 2004). The reduction in absorption at all absorption bands can be due to the aggregation of the photosensitizer in the polar environment.…”